The function 'creature_instance_is_available' should return for each creature spell if the creature has learned it or not. However, for a for me unknown reason, it does not return 'true' for the Drain and Lightning spells.
As this function is used in if-statements related to 'set_players_packet_action', this could very well be the reason why multiplayer games crash as soon as the lightning and drain spells are used.
The function 'creature_instance_is_available' should return for each creature spell if the creature has learned it or not. However, for a for me unknown reason, it does not return 'true' for the Drain and Lightning spells.
As this function is used in if-statements related to 'set_players_packet_action', this could very well be the reason why multiplayer games crash as soon as the lightning and drain spells are used.